1. Technical Field
The present disclosure relates to a rubber composition for a tire tread, and more specifically to a rubber composition for a tire tread that provides a pneumatic tire having excellent wet grip performance, steering stability, and abrasion resistance.
2. Related Art
A pneumatic tire for a high-performance vehicle (hereinafter simply referred to as “tire”) is required to have many performances. Further, examples of the performances include excellent steering stability during high-speed traveling, stability (wet performance) on a wet road surface, and abrasion resistance. In addition, when a vehicle travels at a high speed on the expressway (e.g., autobahn), a circuit or the like for a long period of time, further performance is required for a tire. For example, suppression of change of tire performance is required for a tire. Specifically, a tire is required to suppress a so-called worn tire which exhibits a state of wear of tire surface. Further, a tire is also required to suppress so-called degeneration due to heating in which the steering stability deteriorates by generating heat from the traveling tire rubber. For example, a competitive tire for travel on a wet road surface is required to have excellent wet performance, that is, to have not only excellent wet performance and grip performance, but also to suppress the generation of worn tire and degeneration due to heating when the tire travels at a high speed for a long period of time. Therefore, heretofore, a rubber composition constituting a pneumatic tire, particularly a tread unit thereof for ground contact (hereinafter referred to as a “rubber composition for a tread” or simply referred to as a “rubber composition”) has been intensively researched and developed.
JP-A-2007-321046 discloses a rubber composition for improving the grip performance of a tire in a semiwet state. This rubber composition contains styrene-butadiene copolymer rubber (SBR) having a glass transition temperature (Tg) in a predetermined range. That is, the rubber composition contains 100 parts by weight of styrene-butadiene copolymer rubber (SBR) including any one of single SBR having a glass transition temperature (Tg) of −30 to 0° C. or a blend obtained by mixing two or more kinds of SBR and having an average Tg of −30 to 0° C.; 80 to 180 parts by weight of a filler containing 50 parts by weight or more of silica; and 5 to 60 parts by weight of a resin having a softening point of 100 to 150° C. However, only adjustment of the Tg of the SBR does not necessarily sufficiently satisfy the requirements of users for the wet grip performance, steering stability, and abrasion resistance of a tire.
The present disclosure has been made in view of the problems of conventional techniques. An object of the present disclosure is to provide a rubber composition to be used for a tire tread having excellent wet grip performance, steering stability, and abrasion resistance as compared with a conventional rubber composition.